C1. Congenital conditions (Anterior) Flashcards
what is coloboma? 7 structures affected?
Incomplete closure of the embryonic orbital fissure (during embryological development)
Can affect several structures:
lids, iris, ciliary body, lens, retina, choroid or optic disc
May co-exist
what is iris coloboma?
“Typical” iris colobomas are located in the inferonasal quadrant. They are caused by failure of the embryonic fissure to close in the 5th week of gestation, resulting in a “keyhole-shaped” pupil.
2 consequences of iris coloboma?
photophobia in bright conditions
glare
Mx for iris coloboma?
special contact lens fitted that covers the keyhole-shaped pupil and makes it look round
improves the cosmetic appearance of the eye as well as reducing light sensitivity
For some people, surgery is an option, where the gap in the iris is sewn together to correct the pupil shape and reduce light sensitivity.
what is lens coloboma?
flattening of the equator of the lens in an area of absence of zonular fibers.
best visualized in a dilated eye and may be incidentally diagnosed as they are almost always asymptomatic
consequences of lens coloboma?
Vision may be affected because of the change in lens shape caused by a notch or dent.
There may also be some degree of cataract in the affected eye
can cause symptoms such as blurred or misty vision, colours appearing dull and glare
Mx for lens coloboma?
Refractive error should be treated with corrective lenses.
If severe and unable to correct with manifest refraction, consider lens extraction with IOL placement to prevent amblyopia from developing.
Care should be taken, however, as zonular abnormalities exist and may complicate surgery.
Mx for colobomas in general?
No medication or surgery that can cure or reverse coloboma and make the eye whole again
Correcting any refractive error with glasses or contact lenses.
Maximizing the vision of the most affected eye in asymmetric cases
Ensuring that amblyopia (lazy eye) does not develop in childhood in case of asymmetry.
Sometimes amblyopia treatment (patching, glasses and/or drops) can improve vision in eyes even with severe colobomas.
Treating any other eye condition that may be present with coloboma, such as cataracts.
Treating any complications that might arise from a retinal coloboma later in life, such as the growth of new blood vessels at the back of the eye (neovascularization) and/or retinal detachment.
Using low vision devices
Genetic counselling
what is megalocornea? what gene type? systemic association?
HVID of 13mm or larger
X-linked recessive, 90% affected are males
Systemic associations: Marfan syndrome, Ehlers-Danlos syndrome, Down syndrome
Ocular associations with megalocornea?
Associated with high myopia and astigmatism
Deep anterior chamber
Normal vision and IOP
assessments and mx for megalocornea?
Assessment::
Rule out congenital glaucoma
Mx:
Px reassurance and education
what is microcornea? AD or AR?
HVID of 10mm or less
Autosomal dominant
associations with microcornea?
Associated with hyperopia and shallow anterior chamber
Normal vision
assessments and mx for microcornea?
Assessment
Risk of high IOPs
Plan
Routine glaucoma screening
what is aniridia?
Bilateral absence of the iris, can be total or small stump of the iris base (iris hypoplasia)
associations with aniridia?
Ectopia lentis
Cataract
Foveal & optic nerve hypoplasia
Nystagmus
Conjunctivalization of the peripheral cornea
SSx of aniridia?
Glare
Poor vision, 6/60 or worse
Dry eyes
assessment and mx for aniridia?
Assessment:
Check for glaucoma
Mx:
Cosmetic CL
Low vision aids
Sunglasses
Artificial implantable iris
Refer for genetic counselling
what is albinism?
Melanocytes are present but do not produce melanin
White hair, pale skin, pink eyes
subjective and objective for albinism?
Subjective:
-Poor vision
-Photophobia
Objective:
-VA to worse than 6/120
-High myopia and astigmatism
-Nystagmus
-Macular hypoplasia
-Poor RPE function
assessment and mx for albinism?
Assessment:
Handle px with meticulous care
mx
Low vision aids
Refer for genetic counselling
Dark sunglasses
Good protection against UV (they are easily sunburnt)
what is heterochromia irides?
Asymmetric colour of the two irides
Can be congenital or secondary to disease process
assessment and Mx for heterochromia?
Assessment
DDx: Fuchs heterochromia cyclitis, siderosis, iris melanosis, iris melanoma
Mx:
Px reassurance and education
Photodocument
what is persistent pupillary membrane?
Strand of iris linking to iris
Can be broken due to pupil dilatation
Sticks on anterior lens capsule or
Floats in anterior chamber
Mx for persistent pupillary membrane?
Management
During the first year of life, most PPMs undergo atrophy and require no treatment.
Membranes persisting after one year are less likely to regress spontaneously, increasing the risk of deprivational amblyopia.
Small PPMs can be managed conservatively. Mydriatics, refractive correction, and patching for amblyopia have been used successfully in such cases.
Thick, fibrotic membranes may require surgical excision. Surgery is generally performed in the first weeks or months of life, with good visual prognosis
what is ectopia lentis? cause?
Ectopia lentis is the dislocation or displacement of the natural crystalline lens.
Caused by weakened or deformed zonules
define a luxated lens and a subluxated lens
The lens is defined as luxated (dislocated) when it lies completely outside of the hyaloid fossa, is free-floating in the vitreous, is in the anterior chamber, or lies directly on the retina.
The lens is considered subluxed when it is partially displaced but remains within the lens space.
subjective and objective for ectopia lentis?
Subjective:
monocular diplopia
Objective:
Onset in teenagers
Myopia and astigmatism
Mx for ectopia lentis?
Annual monitoring of VA and Rx to prevent refractive amblyopia
Advised against contact sports
As many predisposing diseases are hereditary, genetic counselling may be indicated
